Ship propelling unit



June 18, 1963 Filed July 7, 1960 P. PISA SHIP PROPELLING UNIT 5 Sheets-Sheet 1 INVENTOR.

Pietro isa.

' WM, wwma June 18, 1963 P. PISA 3,093,961

SHIP PROPELLING UNIT Filed July 7, 1960 5 Sheets-Sheet 2 IN V EN TOR.

EL 6 ti-o 5a. BY

Abba June 18, 1963 PISA SHIP PROPELLING UNIT 5 Sheets-Sheet 3 Filed July '7, 1960 INVENTOR. ?/C a 1' o P; 3* BY WM, flw tdw P. PISA SHIP PROPELLING UNIT June 18, 1963 5 Sheets-Sheet 4 Filed July 7, 1960 INVENTOR. Pam F4.

WM, W M

June 18, 1963 P. PISA SHIP PROPELLING UNIT Filed July 7. 1960 5 Sheets-Sheet 5 INVENTOR. PA :1. H Pi SA.

M m mama v BY United States Patent 3,093,961 SHIP PROPELLING UNIT Pietro Pisa, 76 Lungotevere Flaminio, Rome, Italy Filed July 7, 1960, Ser. No. 41,318 Claims priority, application Italy Feb. 9, 1960 6 Claims. (Cl. 60--35.5)

The present invention relates to a unit suitable for propelling a ship, the thrust created by said unit being supplied by the reaction to the outlet of a water jet thrown rearwards by a special rotary mechanism.

One embodiment of the ship propelling unit is shown only by way of example in the attached drawings where- FIG. 1 is a cross-sectional view taken along the vertical plane X--X of FIG. 2;

FIG. 2 is a longitudinal cross-sectional view of FIGS. 1 and 3 taken along the horizontal plane Z-Z;

FIG. 3 is a cross-sectional view taken along the vertical plane YY of FIG. 2;

FIGS. 4, and 6 show details of the centrifugal impellers of the rotary mechanism and of the system for driving the impellers; more specifically, FIG. 4 is a crosssectional view taken along the line S-S of FIG. 1, FIG. 5 is a cross-sectional view along the line M-M of FIG. 6 and FIG. 6 is a cross-sectional view along the line N--N of FIG. 5;

FIGS. 7 and 7A show how the blades of the two irnpellers forming the rotary mechanism are located during their rotation; particularly, FIG. 7 is front view and FIG. 7A is a cross-sectional view of the cylindrical surfaces along the line RR of FIG. 7 developed on a plane;

FIGS. 8 and 9 show the installation of the propelling units aboard of big ships;

FIG. 10 diagrammatically shows how the inner spherical surface of the rotary mechanism is contacted by the water; and

FIG. 11 diagrammatically shows how the centrifugal forces develop within the rotary mechanism and, the reactions occurring on the restraints or supports.

The propelling unit is essentially comprised of a rotary mechanism the operation of which is very similar to that of a centrifugal pump.

Two conical surface discs 2 are rigidly fixed to the two hollow shafts l the axes of rotation of which lie in the horizontal plane Z--Z and are each inclined on the same side through an angle with respect to the plane X-X (FIG. 2); the apexes of said conical surfaces are coincident with the centre 0 of the system or common point of the axes of the two shafts.

The blades 3 equispaced from one another and mounted on said discs along generatrices of the conical surfaces form the impellers fixed to the two shafts; the blades 3 have the shape of circular annular segments (FIGS. 1, 2 and 6). The outer circular edges of the blades 3 in any position of the impellers slide on the inner spherical surfaces of the two shells 4 forming the housing of the rotary mechanism, and likewise the inner circular edges of the blades slide on the spherical surface of the central sphere 5 pivoted at the ends of the hollow shafts 1 (FIGS. 1, 2 and 3).

Due to the obliquity of the hollow shafts 1 the central sphere 5 thereby supported remains stationary being prevented from rotating due to the aforesaid reasons (FIG. 2).

The corresponding pairs of blades 3 carried by the two opposite discs 2 are all inclined, with respect tothe planes normal to the conical surfaces at a small angle and the blades of one of the discs precede those of the other disc (FIG. 7A).

As shown in FIG. 7A, which shows the cross-sectional 3,093,961 Patented June 18, 1963 view of the blades 3 of the two impellers taken along a cylindrical surface (cross-section R--R of FIG. 7) and developed on a plane, by such an arrangement the corresponding blades do not strike against one another during their rotation.

The blades 3 slidably contact only at two points (1) and (2) located at those positions where the conical surfaces of the two discs 2 are closest (FIG. 7A).

The corresponding blades at the points (1) and (2) come into contact along a radius of the sphere having its center at 0, since the surfaces of the blades 3 consist of an envelope of radii of the same sphere having its center at 0.

These pairs of blades 3 define a plurality of chambers wherein the volume confined thereby and by the stationary spherical portions of the shells 4 and of the central sphere 5 is continuously variable; i.e. through one revolution of the rotary mechanism the volume of one of these chambers changes from a minimum to a maximum and back to a minimum after a 360 revolution.

The variation of the volume of said chamber is due to the obliquity of the two hollow shafts .1 carrying the discs 2; said variation occurs sinusoidally as shown in FIG. 7A.

The greatest volumes of the two chambers are always at that side where the two conical surfaces of the discs 2 are most spaced apart; while the minimum volumes are at the diametrically opposite side (FIGS. 2, l0 and 11).

The water which fills these variable volume chambers exerts, due to the centrifugal force, certain pressures against the spherical inner walls of the shells 4, and the forces resulting from these pressures are proportional to the volume of mass of the water enclosed within said chambers or to the extent of the spherical surface of the housing contacted by the water.

With respect to the vertical plane passing through X-X (FIGS. 2, 3 and 12) all centrifugal forces corresponding to the greatest water masses originate certain differentials with respect to these forces which occur in the diametrically opposite and smaller chambers.

This set of different centrifugal forces forms the dif- V ferential centrifugal field, and the resultant of all these positive dilferences between the centrifugal forces, diametrically opposite with respect to the vertical plane XX, is the differential centrifugal force or static thrust S which is directed horizontally and has constant direction and magnitude (FIGS. 2, 3).

Obviously, for a correct operation of the propelling unit it will be necessary that all chambers defined between the blades are always filled with liquid.

The centn'fugal force contributes to this function, which force, due to the rotational movement of the blades throws the water against the inner spherical walls of the shells 4 and then towards the outlet ducts, drawing from outside other liquid to fill said chambers.

The path through the rotary mechanism must be always radial as in centrifugal pumps, and to this purpose the water conveyed by the hollow shafts 1 enters into the central sphere 5, moves radially through the chambers of the rotary mechanism llowing out and then laterally of the spherical walls of the shells 4- (FIGS. 1 and 2). The water channelled towards the rotary mechanism enters into the central sphere 5 then moves through the aperture 6 at the top between the two parts forming said sphere (FIGS. 1 and 3), to reach the chambers defined by the pairs of blades 3 when the latter travel along the upper half circumference, i.e. when the the chambers are in their expansion stage (FIGS. 1 and 3).

The central sphere 5, on the contrary, is provided with no aperture in the lower half circumference (FIGS. 1

and 3).

The water flowing out of the sphere 5 flows in a direction as determined by the vanes 7 located across the aperture 6 in order to prevent the inflowing liquid from striking against the blades 3 (FIG. 3).

The chambers during-their travel along the lower half circumference are in their volume shrinking stage and therefore said chambers must exhaust water through the apertures 8 located at the sides of the two shells 4 (FIGS 2 and 3). During this stage no entrance of new water must occur. 7

Through the conical walls of the discs 2, and between the blades 3 are provided the inlet ports of the bent ducts 9 which serve the purpose of allowing the passage of the water when the terminal ports of the bent ducts 9 pass under the aperture 8 (FIGS. 2 and 6). Obviously, during the path of the upper half circumference, or filling stage no exhaust of the water towards the outside occurs.

The pressure of the liquid within this rotary mechanism like in centrifugal pumps, is not created by the presure exerted on the liquid by the walls of the blades and of the conical discs, but is only determined by the centrifugal force, which is originated due to the rotational movement imparted to the water by the blades 3. Even if the chambers confined between the blades 3 are not isolated from one another (FIG. 7A), the liquid can not fiow between the contiguous chambers in reverse direction to the movement of rotation of the rotary mechanism, since in that portion where the conical discs are closest, the blades 3 contact with one another at the points (1) and (2) thus continuously creating two dams against the return movement of the water stream (FIG. 7A). The centrifugal action that this rotary mechanism exerts on the liquid is determined by the blade pairs, which impart throughout the entire revolution a thrust to the liquid or blade pressure, quite similar to that exerted by the blades of an ordinary centrifuge, wherein the drawing action occurs towards the center of the impeller and throughout the inner inlet circumference and the outlet throuhgout the outlet outer circumference.

The difference in the operation of this special rotary mechanism as compared to the operation of a centrifugal pump is that in this rotary mechanism the water inlet is allowed only for those chambers which are in a filling or volume expansion stage while said inlet is prevented for the diametrically opposite chambers which are in the exhaust or volume shrinking stage (FIG. 3). This is accomplished by the central sphere 5, which is provided with the semicircular aperture 6 only along the upper semi-circumference, i.e. in the portion where the volumes of said chambers increase (FIGS. 1 and 3, and 7A).

Likewise the outlet of the liquid from the rotary mechanism is prevented in the upper portion where the shells 4 have no outlet port and along the upper semi-circurnference where the chambers are in the expansion stage or filling stage (FIGS. 2, 3 and 7A).

The outlet of the water is possible on the contrary along the subsequent lower semi-circumference where the terminal ports of the bent ducts 9 come opposite to the stationary apertures 8 for the outwards discharge, said ports being located only in that portion where the chambers are in the volume decrease or exhaust stage (FIGS. 2 and 7A).

In this rotary mechanism as compared to centrifuges, no direct communication exists between the inlet port 6 and the outlet ports 8; the contrary condition would result in the chambers defined between the blades permitting a direct passage of water with the possibility of a too rapid exhaust.

In order not to alter the value of the centrifugal forces (which are proportional to the water masses), against the spherical inner walls of the shells 4, the chambers comprised between the blades must always be filled with liquid.

To this purpose the apertures 8 which are located lateral-ly in the shells 4 and along the lower half circumference, have a non uniform width, i.e. said apertures are narrow at their ends and wide at their center (FIGS. 2 and 7A). Therefore, in front of the terminal apertures of the bent ducts 9 the areas for the passage of the liquid vary from a minimum to a maximum and vice-versa back to a minimum, to afford an outlet area which is always proportional to the amount of the water which is expelled from the chambers of the rotary mechanism along the path of the lower half circumference.

The apertures 8 behave like gauged apertures which allow, due to the resistance thereby afforded, the passage of only a certain amount of liquid in order to keep the chambers whose volumes are decreasing or in the exhaust stage always filled with water. 7

Likewise, the inlet port 6 into the rotary mechanism,

located in the upper portion of the sphere 5 is narrow at its ends and wide at its center in order to keep the inlet cross-sectional areas into the chambers defined be tween the blades proportional to the volume variations which occur in said chambers.

Therefore both the relative inlet speed into the rotary mechanism and the relative outlet speed therefrom are constant in the respective inlet and outlet ports 6 and 8 respectively, as the ratio Volume Cross-sectional area is always maintained, said ratio being the value of the relative speeds.

This fact is very important since the vortical movements are thereby reduced within the rotary mechanism, and the water is capable of maintaining, as in the usual centrifuge, a path approximately parallel to the fluid streams, at an almost constant speed, and thus a permanent rate in passing through the ducts defined by the blades.

The outlet ports 8 and the inlet ports 6 (in dotted line in FIG. 7A) are located along the lower half circumference, and along the upper half circumference respectively.

The existence of this static force, or diiferential centrifugal force can be easily understood from the examination of FIG. 10 which represents the spherical surface (hatched) of the housing of the rotary mechanism contacted by the water.

That part of the surface which is at the left hand side of the vertical plane whose trace is the line XX is less than the part located at the right hand side.

The difference between the aforesaid surfaces is represented by the two bands located laterally of the central surface (hatched with horizontal lines-FIG. 1-0) against which the liquid pressure acts.

The resultant of these unbalanced centrifugal forces P is the dilferential centrifugal force or static force S (FIG. 10).

The liquid within the rotary mechanism presses against the conical walls of the two discs 12, or impellers with a pressure directed at right angles thereto, and the value of said pressure is the average value of the water pressures at its inlet and at its outlet.

The pressure due to the centrifugal force increases with the square of the radius of the rotary mechanism.

The resultants N of these pressures (given by the surfaces of the conical walls multiplied by the average pressure) are directed at right angles to the conical surfaces; and said forces combine into two forces'M directed along the axes of the conical discs 2 of the rotary mechanism.

These forces M have in turn a resultant C which represents the static counter thrust or restraint reaction and is directed contrary to the static forces.

This counter thrust C is far less than the thrust S due to the centrifugal differential field; the dilference gives the net value of the static thrust S.

The water issuing from the rotary mechanism enters into the volute It or diffuser and possesses an absolute outiiow speed C which is the resultant of the peripheral outer speed V of the impellers 2 and of the relative outflow speed W (FIG. 3). The absolute outflow speed C is high and is reduced through the passage through the volute and results in transforming the kinetic energy into pressure energy. It will be convenient that the outflow speed of the water from the ship through the outlet ports 11 (FIG. 3) will approximate twice the forward speed of the ship since under these conditions the maximum efliciency of the reaction thrust will be obtained. The thrust exerted by the water at the outlet from the volute 10 is formed partially by the action of the pressure differential of the liquid in the outlet section 11 with respect to the pressure of the outer water (difference of hydrostatic pressures) and partially by the reaction due to the speed of the outllowing jet (dynamic pressure).

The high driving moment which is necessary for moving the two impellers or discs 2 is transmitted by the shaft 12 which is coupled directly to the shaft of a turbine or other high speed prime mover (FIG. 1).

By a bevel coupling 13-14 the number of revolutions of the vertical shaft 14 is greatly reduced (FIG. 1).

The shaft 15 carries at its lower and the central wheel 16 which is in mesh with two laterally located spur gears 17 (FIGS. 1 and 4).

At their lower ends each of the shafts 18 carry a worm 19 (FIGS. 2 and 4).

These worms 19 are in mesh with helical gears 2i) which are mounted on the ends of the hollow shafts 1 (FIGS. 1 and 5).

Each worm gear is enclosed within an oil filled box 21 which is located laterally of the sides 22 of the propelling unit (FIGS. 1 and 2).

The two worms 19 are both on the same side of the vertical plane (FIG. 2) and said worms have the same direction of rotation and therefore also the two helical gears 24 rotate in the same direction.

Thus the simultaneous and equal rotational movement for both conical discs or impellers 2 is provided, this being a necessary condition to prevent the corresponding blades 3 from striking against one another (FIG. 7A).

The two shells 4 forming the casing have their lower portion resting on a base or circular platform 23, these supports being internally provided with a duct which continues the shape of the walls of the volute 10 for collectiug the water issuing from the rotary mechanism. Two discharge ducts 20 located under the platform 23 and in contact with the sea water have at their ends the ports 11]. for the outflow of the jet, said ports being directed in the opposite direction to the forward movement of the ship (FIGS. 3 and 8). In the circular platform 23 are also provided the apertures 24 for the water intake from. outside, said water being conveyed at the free ends of the two hollow shafts 1 through the pair of goose necked ducts 26 (FIGS. 1, 2 and 3).

Also in the lower wall of the platform 23 are provided the two elbow shaped ducts for the water intake protected by a grid 28 to prevent foreign matter from entering into the rotary mechanism (FIG. 3). These intakes 27 are directed in the direction of the forward movement of the ship in order to use the forward speed of the ship as the inflow speed of the water into the propelling unit (FIG. 3). The circular platform or base of the rotary mechanism is capable of rotating about its vertical axis coincident with the axis of the shaft 15 (FIGS. 1 and 3); therefore the propelling unit can be driven for any position assumed by the platform 23 and also during the rotation thereof. The platform 23 whereon rests the rotary mechanism is supported by six rim wheels 29 said wheels running along a circular rail 30 which is rigidly secured to the ships bottom structure (FIGS. 1 and 3).

In order to prevent the high Weight of the rotary mechanism from resting only on the rail 30, the large plate 31 which supports the vertical shaft 15 (FIGS. 1 and 3) is provided with six wheels 32, which run on another upper circular rail 3 which is rigidly secured to the frame 34 of the entire propelling unit.

Above the members carrying the stub shafts for the wheels 29 a toothed ring 35 is located and said toothed ring engages a conical pinion 36 rigidly secured to the spindle 37 supported by the frame 34 (FIGS. 2 and 3).

It will be possible to have the entire unit rotated through 360 by a quick operation.

The direction of the total thrust imparted to the ship depends upon the position of the circular platform 23 with respect to the longitudinal axis of the ship.

:By having the platform rotatable about its axis it will be possible to cause the thrust to assume any direction.

In FIG. 8, showing a big ship provided with two separate propelling units, has been shown an arrangement by which it is possible to cause the ship to turn about its vertical axis by providing for the two units to move to positions in which there are produced two contrary thrusts directed at right angles to the longitudinal axis of the ship. The possibility of having the sidewards directed thrusts makes the ship highly maneuverable, particularly when the ship is coming to a quay or fending off therefrom.

FIG. 9 shows a combined system where a screw propeller is provided together with a reaction propulsion means; in this case the propelling unit serves the purpose of auxiliary motive means particularly when in open sea in order to increase the speed of the ship. In both the arrangements of FIGS. 8 and 9 the propelling units are located below the water-line and thereby the rotary mechanism is always filled by seawater, this being a necessary condition in order to have immediately available the centrifugal action produced by the impellers.

The elastic sealing rings 38 located about the circular edge of the platform 23 prevent the sea water from enterintg through the circular clearance existing between the platform and the wall of the ships bottom (FIGS. 1 and 3).

The pressure of the outer water acts to sequeeze said rings preventing the liquid from entering. When the ship is at rest, in the absence of the high inlet speed of the water into the intakes 27, the dynamic thrust due to reaction is reduced.

The water moving through the elbow duct 27 carrying the intake mouth (FIG. 12) exerts against the walls of said duct a thrust R which is contrary to the forward movement of the ship.

Likewise, the water along the outlet volute 10 exerts against the walls thereof a thrust R contrary to R The values of these two contrary thrusts can be considered to be equal to one another.

The propelling unit which draws the water from outside and then discharges said water with a greater speed and a higher pressure, continuously creates by the passage of the water through the rotary mechanism a thrust due to the reaction of the outflowing jet (dynamic thrust).

In order to create the static thrust S it will be necessary that the liquid will exert against the spherical walls of the casing a pressure which is inherent in the static head (the static head is proportional to the difference between the inner and outer peripheral speeds of the impellers to which is added the difference between the inlet and outlet relative speeds in the ducts comprised between the blades) V5 V? W; W?)

The static head is a pressure possessed by the liquid at the outlet from impellers and which is available for being utilized as a thrust due to the reaction exerted by theoutfiow jet against the sea water.

The dynamic head is proportional to the absolute outflow speed with which the liquid leaves the impeller (Static head H (Dynamic head H= 9 In the terminal port 11 (FIG. 3) for the exhaust to aoeasei 7 outside, the water possesses the aforesaid static head (static H) to which is added the pressure increment due to the slowing down of the absolute outlet speed C in the passage of the water through the volute 10.

This total pressure,, from which are subtracted the passive resistances encountered by the water flowing through said path, exerts in the outlet port 11 a thrust due to the difference of pressure between the liquid at that point relative to the pressure possessed by the sea water.

To this propelling action the propelling action due to the outflowing jet is to be added, and the value of this action is given by the momentum possessed by the liquid at that point. (Momentum-mass or water rate in 111. per sec. times the outflow speed in metres per sec.)

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the form hereinbefore described and illustrated in the drawings being merely a preferred embodiment thereof.

Iclaim:

1. A ship propelling unit, comprising a casing having a spherical part and adapted to be mounted on a ship, two impellers in the spherical pant of said casing each being in the form of a conical disc, two shafts, at least one of which is hollow, rotatably mounted in said casing and on which said conical discs are rigidly mounted, said shafts having the axes of rotation thereof horizontal and intersecting at an obtuse angle to each other at the center of said casing and with the vertices of said conical discs coincident with the point of intersection of said axes of rotation, at central sphere pivoted on and carried by the ends of said shafts with the center thereof coincident with the center of said casing and into which the hollow shaft opens, said central sphere having an opening therein extending along the upper semicircumference thereof and giving access to the space within said casing in the radial direction, said conical discs each having a plurality of blades thereon cooperating with the blades on the other conical disc to form, together with the outer surface of said central sphere and the inner surface of the spherical part of said casing, a plurality of chambers having a continuously changing volume during a revolution of the impellers, said casing having an opening in both sides thereof extending along the lower semicircurnference of the spherical part of said casing for allowing the water discharge, the water stream being always radial in said chambers and having a continuous increase in its centrifugal force, power transmission means connected to said shafts for rotating said impellers at the same speed and in the same direction, an intake connected to said hollow shaft, and a discharge duct on said casing, said casing having an aperture therein opening into said duct, said discharge duct being directed away from said casing from the side thereof opposite the side at which said conical discs are most divergent.

2. A ship propelling unit as claimed in claim 1, wherein the opening extending along the upper semicurcumference of the said central sphere is diamond-shaped and is as long as the semicircumference of the said central sphere, whereby the inlet to the said chambers admits water only to the chambers which have the volume thereof 8, increasing and in an amount always proportional to the volume increase of the chambers during the travel of the blades along the upper semicircurnference of the said central sphere, so that 'theadmission of water to the said chambers always occurs in an amount equal to the volume increase of said chambers and with constant relative inlet speed ratio of the passage area and the volume increase of said chambers being constant at all positions during said travel.

3. A ship propelling unit as claimed in claim 1, wherein the two openings made in the casing laterally of the lower spherical surface of the spherical part of the casing are diamond-shaped and have a length equal to the lower semicircumference of the spherical part of the casing, which openings serve for the outlet of the water in a quantity equal to the decreasing in volume to which the said chambers are subject during the travel along the lower circumference, so that by means of the last mentioned openings said chambers are always kept full of water and too rapid evacuation of the chambers under the action of J the centrifugal force is prevented and constant relative outlet speed is maintained.

4. A ship propelling unit as claimed in claim 1, wherein a plurality of fins are located transversely of the upper aperture in the central sphere and are adapted to direct the water tangentially onto the blades of the discs, whereby shocks and swirling movements of the water are avoided during movement through the inlet to the charmbers in the casing.

5. A ship propelling uni-t as claimed in claim 1, wherein said blades are rigidly mounted on the said discs along the generatrices of the conical surface of the discs, and have the shape of an annular segment with the outer and inner edges a circular are having a common center coincident with the center of the casing, the surfaces of the said blades being formed by a series of radius segments adjacent one to the other and all directed toward the center of the casing.

6. A ship propelling unit as claimed in claim 1 wherein there are an equal number of blades on each disc, the blades on one disc being opposed to the blades on the other disc and the blades of one disc are inclined slightly in the direction of rotation of said discs, while the blades of the other disc are inclined an equal angle in a direction opposite to the direction of rotation, whereby the said nblades do not strike against one another during the simultaneous rotation, but come into sliding contact along successive radii of the said blade and at two positions near to each other and located at the part where the conical surfaces of the discs approach each other closely kin order always to form two wholly closed barriers to prevent the water from passing through the chambers and in a direction opposite to the motion imparted by the impellers to the water.

References Cited in the file of this patent UNITED STATES PATENTS 115,425 Boyrnan May 30, 1871 518,680 Scott Apr. 24, 1894 1,484,881 Gill Feb. 26, 1924 2,242,058 Cuny May 13, 1941 2,654,322 Olsen Oct. 6, 1953 2,828,695 Marshall Apr. 1, 1958 2,831,436 Schmidt et a1. Apr. 22, 1958 

1. A SHIP PROPELLING UNIT, COMPRISING A CASING HAVING A SPHERICAL PART AND ADAPTED TO BE MOUNTED ON A SHIP, TWO IMPELLERS IN THE SPHERICAL PART OF SAID CASING EACH BEING IN THE FORM OF A CONICAL DISC, TWO SHAFTS, AT LEAST ONE OF WHICH IS HOLLOW, ROTATABLY MOUNTED IN SAID CASING AND ON WHICH SAID CONICAL DISCS ARE RIGIDLY MOUNTED, SAID SHAFTS HAVING THE AXES OF ROTATION THEREOF HORIZONTAL AND INTERSECTING AT AN OBTUSE ANGLE TO EACH OTHER AT THE CENTER OF SAID CASING AND WITH THE VERTICES OF SAID CONICAL DISCS COINCIDENT WITH THE POINT OF INTERSECTION OF SAID AXES OF ROTATION, A CNETRAL SPHERE PIVOTED ON AND CARRIED BY THE ENDS OF SAID SHAFTS WITH THE CENTER THEREOF COINCIDENT WITH THE CENTER OF SAID CASING AND INTO WHICH THE HOLLOW SHAFT OPENS, SAID CENTRAL SPHERE HAVING AN OPENING THEREIN EXTENDING ALONG THE UPPER SEMICIRCUMFERENCE THEREOF AND GIVING ACCESS TO THE SPACE WITHIN SAID CASING IN THE RADIAL DIRECTION, SAID CONICAL DISCS EACH HAVING A PLURALITY OF BLADES THEREON COOPERATIANG WITH THE BLADES ON THE OTHER CONICAL DISC TO FORM, TOGETHER WITH THE OUTER SURFACE OF SAID CENTRAL SPHERE AND THE INNER SURFACE OF THE SPHERICAL PART OF SAID CASING, A PLURALITY OF CHAMBERS HAVING A CONTINUOUSLY CHANGING VOLUME DURING A REVOLUTION OF THE IMPELLERS, SAID CASING HAVING AN OPENING IN BOTH SIDES THEREOF EXTENDING ALONG THE LOWER SEMICIRCUMFERENCE OF THE SPHERICAL PART OF SAID CASING FOR ALLOWING THE WATER DISCHARGE, THE WATER STREAM BEING ALWAYS RADIAL IN SAID CHAMBERS AND HAVING A CONTINUOUS INCREASE IN ITS CENTRIFUGAL FORCE, POWER TRANSMISSION MEANS CONNECTED TO SAID SHAFTS FOR ROTATING SAID IMPELLERS AT THE SAME SPEED AND IN THE SAME DIRECTION, AN INTAKE CONNECTED TO SAID 